X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FSwitch.pm;h=c6d3931c267a51cc12236ff149f6e4c5bd1a3eda;hb=be2597dfdde55c276ac6c4b68dadc448c601d0cc;hp=84e28907e6b9a05d540892c7f9718d44919f3998;hpb=b2486830aef359160f82c24b5ca8d2f237006c0a;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/Switch.pm b/lib/Switch.pm index 84e2890..c6d3931 100644 --- a/lib/Switch.pm +++ b/lib/Switch.pm @@ -4,7 +4,7 @@ use strict; use vars qw($VERSION); use Carp; -$VERSION = '2.10'; +$VERSION = '2.12'; # LOAD FILTERING MODULE... @@ -73,7 +73,7 @@ sub is_block } -my $EOP = qr/\n\n|\Z/; +my $EOP = qr/\n|\Z/; my $CUT = qr/\n=cut.*$EOP/; my $pod_or_DATA = qr/ ^=(?:head[1-4]|item) .*? $CUT | ^=pod .*? $CUT @@ -502,26 +502,25 @@ Switch - A switch statement for Perl =head1 VERSION -This document describes version 2.10 of Switch, -released Dec 29, 2003. +This document describes version 2.11 of Switch, +released Nov 22, 2006. =head1 SYNOPSIS - use Switch; - - switch ($val) { - - case 1 { print "number 1" } - case "a" { print "string a" } - case [1..10,42] { print "number in list" } - case (@array) { print "number in list" } - case /\w+/ { print "pattern" } - case qr/\w+/ { print "pattern" } - case (%hash) { print "entry in hash" } - case (\%hash) { print "entry in hash" } - case (\&sub) { print "arg to subroutine" } - else { print "previous case not true" } - } + use Switch; + + switch ($val) { + case 1 { print "number 1" } + case "a" { print "string a" } + case [1..10,42] { print "number in list" } + case (@array) { print "number in list" } + case /\w+/ { print "pattern" } + case qr/\w+/ { print "pattern" } + case (%hash) { print "entry in hash" } + case (\%hash) { print "entry in hash" } + case (\&sub) { print "arg to subroutine" } + else { print "previous case not true" } + } =head1 BACKGROUND @@ -591,14 +590,11 @@ the existence of a series of keys (C{$c}>), one could test for the existence of a single key in a series of hashes (C{$s}>). -As L observes, a Perl case mechanism must support all these -"ways to do it". - - =head1 DESCRIPTION The Switch.pm module implements a generalized case mechanism that covers -the numerous possible combinations of switch and case values described above. +most (but not all) of the numerous possible combinations of switch and case +values described above. The module augments the standard Perl syntax with two new control statements: C and C. The C statement takes a @@ -638,23 +634,14 @@ mechanism: %special = ( woohoo => 1, d'oh => 1 ); while (<>) { + chomp; switch ($_) { - case (%special) { print "homer\n"; } # if $special{$_} - case /a-z/i { print "alpha\n"; } # if $_ =~ /a-z/i + case /[a-z]/i { print "alpha\n"; } # if $_ =~ /a-z/i case [1..9] { print "small num\n"; } # if $_ in [1..9] - - case { $_[0] >= 10 } { # if $_ >= 10 - my $age = <>; - switch (sub{ $_[0] < $age } ) { - - case 20 { print "teens\n"; } # if 20 < $age - case 30 { print "twenties\n"; } # if 30 < $age - else { print "history\n"; } - } - } - + case { $_[0] >= 10 } { print "big num\n"; } # if $_ >= 10 print "must be punctuation\n" case /\W/; # if $_ ~= /\W/ + } } Note that Ces can be nested within C (or any other) blocks, @@ -669,7 +656,7 @@ useful for aggregating integral cases: { switch ($_[0]) { case 0 { return 'zero' } case [2,4,6,8] { return 'even' } - case [1,3,4,7,9] { return 'odd' } + case [1,3,5,7,9] { return 'odd' } case /[A-F]/i { return 'hex' } } } @@ -681,7 +668,7 @@ Fall-though (trying another case after one has already succeeded) is usually a Bad Idea in a switch statement. However, this is Perl, not a police state, so there I a way to do it, if you must. -If a C block executes an untargetted C, control is +If a C block executes an untargeted C, control is immediately transferred to the statement I the C statement (i.e. usually another case), rather than out of the surrounding C block. @@ -698,7 +685,7 @@ For example: If $val held the number C<1>, the above C block would call the first three C subroutines, jumping to the next case test -each time it encountered a C. After the thrid C block +each time it encountered a C. After the third C block was executed, control would jump to the end of the enclosing C block. @@ -713,7 +700,7 @@ For example: case /\d/ { handle_dig_any(); } } -If an untargetted C statement is executed in a case block, this +If an untargeted C statement is executed in a case block, this immediately transfers control out of the enclosing C block (in other words, there is an implicit C at the end of each normal C block). Thus the previous example could also have been @@ -787,17 +774,19 @@ be tested against a series of conditions. For example: sub beverage { switch (shift) { - - case sub { $_[0] < 10 } { return 'milk' } - case sub { $_[0] < 20 } { return 'coke' } - case sub { $_[0] < 30 } { return 'beer' } - case sub { $_[0] < 40 } { return 'wine' } - case sub { $_[0] < 50 } { return 'malt' } - case sub { $_[0] < 60 } { return 'Moet' } - else { return 'milk' } + case { $_[0] < 10 } { return 'milk' } + case { $_[0] < 20 } { return 'coke' } + case { $_[0] < 30 } { return 'beer' } + case { $_[0] < 40 } { return 'wine' } + case { $_[0] < 50 } { return 'malt' } + case { $_[0] < 60 } { return 'Moet' } + else { return 'milk' } } } +(This is equivalent to writing C, etc.; C<$_[0]> +is the argument to the anonymous subroutine.) + The need to specify each condition as a subroutine block is tiresome. To overcome this, when importing Switch.pm, a special "placeholder" subroutine named C<__> [sic] may also be imported. This subroutine @@ -806,11 +795,11 @@ higher-order function. That is, the expression: use Switch '__'; - __ < 2 + __ + __ < 2 is equivalent to: - sub { $_[0] < 2 + $_[1] } + sub { $_[0] < 2 } With C<__>, the previous ugly case statements can be rewritten: @@ -850,7 +839,8 @@ and requires both these modules to be installed. =head1 AUTHOR -Damian Conway (damian@conway.org) +Damian Conway (damian@conway.org). The maintainer of this module is now Rafael +Garcia-Suarez (rgarciasuarez@gmail.com). =head1 BUGS @@ -873,6 +863,6 @@ use smaller source files. =head1 COPYRIGHT - Copyright (c) 1997-2003, Damian Conway. All Rights Reserved. + Copyright (c) 1997-2006, Damian Conway. All Rights Reserved. This module is free software. It may be used, redistributed and/or modified under the same terms as Perl itself.